THE EFFECT OF CHLORAMPHENICOL AND CERTAIN OTHER DRUGS ON THE OXIDATION OF AROMATIC AMINO ACIDS BY A STRAIN OF PSEUDOMONAS AERUGINOSA

¹ Department of Physiology and Pharmacology, Duke University School of Medicine, Durham, North Carolina

1. Chloramphenicol, streptomycin, terramycin and aureomycin inhibit the oxidation and to a lesser extent the deamination of phenylalanine, tyrosine and phenylserine by a strain of Pseudomonas aeruginosa. They also inhibit the oxidation of succinate and certain other dicarboxylic acids.

2. The oxidation of phenylalanine is most sensitive to the action of these drugs. During its oxidation no ammonia is assimilated. During the oxidation of tyrosine and phenylserine part of the ammonia produced is assimilated and this assimilation is inhibited by the drugs.

3. It appears that the antibiotics tested interfere directly or indirectly with the formation of compounds which may be necessary for the assimilation of ammonia or in the case of phenylalanine for its oxidation.

4. Thienylalanine inhibits the oxidation of phenylalanine and phenylserine and to a lesser extent tyrosine. It also inhibits the assimilation of ammonia during the oxidation of succinate. Mandelic acid has no effect on this latter reaction and is only effective in inhibiting the oxidation of phenylalanine in the acid range.